JCB P2732-13 – PCM/TCU: Y Solenoid Open Circuit

The Transmission Control Unit (TCU) or Powertrain Control Module (PCM) has detected an electrical open circuit or short to ground in the 'Y' transmission solenoid (also known as the mainshaft solenoid) circuit. This indicates a broken wire, a disconnected plug, or an internal failure of the solenoid coil itself, which will disrupt normal transmission operation.

• 3CX
• 4CX
• 5CX
• 536-70
• TM310

1. 1

   Visually inspect the wiring harness leading to the transmission solenoid block for any signs of damage, such as chafing, melting, or corrosion.

2. 2

   Inspect the electrical connectors at the solenoid block for bent or corroded pins.

3. 3

   Check the transmission fluid level and condition, as low or dirty fluid can cause secondary transmission issues.

4. 4

   Locate the 'Y' solenoid on the hydraulic control block (typically the middle solenoid on the bottom bank on 4-speed powershift models). Access may require the removal of a side panel under the operator's cab on 3CX and 4CX models.

5. 5

   Perform a continuity and resistance check on the solenoid coil and the wiring between the ECU and the solenoid.

1. 1

   Safety First

   Ensure the machine is parked on level ground, the parking brake is engaged, and the engine is off. Disconnect the battery to prevent electrical shorts.

2. 2

   Locate the Solenoid

   Access the transmission solenoid block as identified in the diagnostic checks. The solenoids are typically labeled (T, U, V, W, X, Y, Z).

3. 3

   Disconnect the Connector

   Carefully disconnect the electrical connector from the 'Y' solenoid.

4. 4

   Test the Solenoid

   Using a multimeter, measure the resistance across the two pins of the solenoid. Compare this reading to the manufacturer's specification if available. If the reading is out of specification (e.g., infinite for an open circuit), the solenoid is faulty and needs to be replaced.

5. 5

   Test the Wiring

   If the solenoid tests within specification, the fault lies in the wiring harness. Check for continuity from the ECU connector to the solenoid connector. Repair any breaks or shorts found in the wiring.

6. 6

   Replace the Solenoid

   If the solenoid is confirmed to be faulty, unscrew it from the valve block. Be prepared for some transmission fluid to leak out.

7. 7

   Install the New Solenoid

   Screw the new solenoid into the valve block and tighten it to the manufacturer's specified torque.

8. 8

   Reconnect and Reassemble

   Reconnect the electrical connector and reassemble any panels that were removed for access.

9. 9

   Clear Fault Codes

   Reconnect the battery, start the machine, and clear the fault codes using a diagnostic tool.

10. 10

    Test Operation

    Operate the machine and test the transmission to ensure that the fault has been resolved, paying particular attention to the engagement of 4th gear if applicable.